1. Field of the Invention
The present invention generally relates to trailers, and more particularly relates to semi-trailer sidewall constructions and methods of making the same.
2. Related Art
There are at least three known semi-trailer sidewall constructions commonly in use that have some similarity in design. These trailer sidewall constructions include a shaped aluminum post spaced between a plurality of panels. The posts are also installed between the panel joints on the panel to give the wall added strength. One construction includes posts that are exposed on the exterior of the trailer and the panels are abutted end-to-end to provide a flush panel arrangement on the interior side of the trailer. This construction may require relatively thick posts (about 1–2 inches), has a single wall of moisture resistance material, has a normal level of strength and durability, is not easy to decal because of the exposed posts, has less marketability as the market desires smooth sided trailers, and has large amounts of wind resistance from the exposed posts.
Another construction includes posts that are exposed on the interior of the trailer and the relatively thin panels are abutted end-to-end to provide a flush panel arrangement on the exterior side of the trailer. In this construction, the posts are covered on the interior of the trailer with plywood or other protective material and the posts are about ½–2 inches thick to provide the necessary strength and stiffness. This construction requires lining to make the inside of the trailer sidewall flush. As the wall becomes thinner the number of posts needed and/or the required strength of each post must increase, making the thin wall versions of the interior post trailers become quite heavy. The interior lining on interior post trailers are can be a source of extra maintenance. Also this type of trailer normally requires scuff liner at the floor to protect the interior liner that adds weight and cost and is a source of extra maintenance. Both exterior post and interior post trailers draw much of their sidewall strength from the posts.
A further construction comprises a composite panel consisting of a sheet of metal chemically bonded to a plastic filler and then another sheet of metal bonded to the plastic filler. Composite trailers do not require posts. The multi-layered panels have an inherent stiffness and strength that eliminate the need for supporting posts. This configuration has several disadvantages including difficulty to repair, possibly heavier than other sidewall constructions depending on the wall thickness of the composite panel, and the panels are much more complicated to build and require a very special manufacturing process to bind the metal to the plastic core.
A semi-trailer sidewall construction that addresses these and other disadvantages of known sidewall constructions would be an advance in the art.